- One of a comprehensive range of Premier Hand Tools, suitable for daily professional use. - Manufactured from hardened and tempered high grade Chrome Vanadium 6142 steel. - Fully polished mirror finish for resistance to corrosion. - Feature specially machined flutes in the walls of the socket which enable use on up to 85% rounded fasteners. - This not only provides added strength but also prevents damage to worn or rusted fixings. - Contents: 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4", 13/16", 7/8", 15/16". - Includes knurled ring for extra grip with oily fingers. - Supplied on socket rail. - Lifetime guarantee*.